Growths that develop on the inner lining of the stomach are known as gastric polyps. A gastric polyp is an abnormal growth of cells that projects from the mucosal surface into the stomach’s hollow space, or lumen. These formations vary significantly in size, shape, and cellular composition. Gastric polyps are a relatively common incidental finding, occurring in roughly 2% to 6% of individuals who undergo an upper gastrointestinal endoscopy. While most gastric polyps are benign (non-cancerous), certain types carry a specific risk of becoming malignant over time. Understanding the classification of these growths is important for determining a patient’s long-term risk profile.
Categorizing Gastric Polyps
The classification of a gastric polyp is based on its histology, or the specific cellular makeup revealed under a microscope, which directly relates to its potential for malignant change. The majority of gastric polyps fall into three main categories: fundic gland polyps, hyperplastic polyps, and adenomas.
Fundic Gland Polyps (FGPs)
FGPs are the most frequently encountered type, often accounting for up to 77% of cases. These growths form in the upper part of the stomach (the fundus) and have virtually no potential for becoming cancerous. FGPs typically appear as small, smooth bumps and are often multiple.
Hyperplastic Polyps (HPs)
HPs are the second most common type. They arise from prolonged irritation or inflammation of the stomach lining, often associated with chronic gastritis. The risk of malignant transformation in hyperplastic polyps is low (less than 2%), but this risk increases significantly for polyps exceeding 1 centimeter in diameter.
Gastric Adenomas
Adenomas are the least common type, but they are the most significant due to their risk profile. Adenomas are considered neoplastic, involving abnormal cell changes (dysplasia) that can precede cancer. The risk of an adenoma progressing to cancer can be substantial, reaching 30% for polyps showing high-grade dysplasia. Because of this high malignant potential, adenomas require aggressive management.
Identifying the Causes and Symptoms
The underlying causes for gastric polyp formation are varied and depend on the specific type of polyp. Chronic inflammation of the stomach lining (gastritis) is a major contributing factor for hyperplastic polyps and adenomas. This persistent inflammation causes mucosal cells to proliferate abnormally.
Causes of Polyp Formation
Infection with the bacterium Helicobacter pylori (H. pylori) is a common driver of chronic gastritis. This infection is strongly linked to hyperplastic polyps, and successful eradication of the bacteria often leads to the regression or disappearance of these polyps. H. pylori infection is also implicated in the pathway leading to the formation of gastric adenomas.
Another cause is the long-term use of Proton Pump Inhibitors (PPIs), medications prescribed to reduce stomach acid. Chronic acid suppression increases the hormone gastrin, which stimulates the growth of glandular cells. This effect commonly causes fundic gland polyps, though these PPI-associated polyps remain overwhelmingly benign.
Symptoms
Most gastric polyps are small and grow slowly, so the majority of patients experience no noticeable symptoms. They are typically discovered incidentally when a patient undergoes an upper endoscopy for an unrelated health concern.
When symptoms occur, they are usually related to the polyp’s size or the presence of an ulceration on its surface. Larger polyps can cause vague abdominal pain, nausea, or a sense of fullness after eating. If a polyp ulcerates, it can cause slow, chronic blood loss. This blood loss can deplete iron stores, resulting in iron-deficiency anemia, which manifests as fatigue and paleness. In rare cases, a very large polyp can obstruct the passage of food, leading to vomiting or severe indigestion.
Diagnosis and Management Approaches
The definitive diagnosis of a gastric polyp begins with a procedure called upper endoscopy, or esophagogastroduodenoscopy (EGD). During an EGD, a thin, flexible tube equipped with a camera is passed through the mouth and esophagus into the stomach, allowing a gastroenterologist to visually inspect the stomach lining. The endoscopist notes the size, location, and general appearance of any growths found.
Visual inspection alone is not sufficient to determine the risk level. Therefore, a tissue sample (biopsy) is taken from the polyp during the endoscopy. This small sample is sent to a pathologist for microscopic examination, which is the only way to accurately classify the polyp as a fundic gland polyp, hyperplastic polyp, adenoma, or another, less common type. The pathologist’s report, which confirms the histology and checks for any signs of dysplasia, is the cornerstone of the management plan.
Management for gastric polyps varies widely based on the histological type and size.
Surveillance and Removal
For small, asymptomatic fundic gland polyps that are not associated with a genetic syndrome, a strategy of surveillance is often adopted. These low-risk polyps typically do not require immediate removal and may only need occasional monitoring during future endoscopies.
Conversely, all gastric adenomas are generally recommended for removal due to their significant potential for malignant transformation. This removal is most often performed endoscopically through a procedure called polypectomy, where specialized instruments are passed through the endoscope to safely excise the growth. Polypectomy is also recommended for any polyp larger than 1 centimeter, regardless of its initial visual appearance, as size is a strong predictor of risk.
Addressing Underlying Causes
Beyond removal or monitoring of the polyp itself, addressing any underlying causes is an important management step. For instance, if the pathology report suggests a hyperplastic polyp associated with H. pylori infection, a course of antibiotics to eradicate the bacteria is recommended. Treating the underlying infection reduces inflammation and may cause the hyperplastic polyp to shrink or resolve completely, which also helps reduce the risk of future polyp formation.